SETI in My Inbox

One of the nice things about being a semi-pro blogger is that people send me tips about things that might be blogworthy. Most of these go into the daily links dump posts, but every now and then one hits at a time when I'm short of material, and looking for something to write about.

Such as the email that came in last night from KQED in San Francisco, plugging a video about the Search for Extra-Terrestrial Intelligence (SETI) project, and the new Allen Telescope Array that's expected to speed the search up by a few orders of magnitude.

There's a lot to like, here. It's a well-made video, with absolutely no speculation about the wonders of potential alien technology, and the absolute minimum contractually required existential "are we alone?" crap.

It's also got excellent, concise explanations of both the scale of the problem (just how many star systems are we trying to look at?) and how the search works. How you detect alien signals without knowing exactly what you're looking for is a common source of confusion about this stuff, and the video does a good job of explaining the trick.

Basically, you look for fairly intense signals that are limited to a very narrow range of frequencies. Natural processes tend to generate radiation over a very broad range of different frequencies, but if you're trying to send a message, you generally want to restrict that to make it easier to build antenna systems for sending and receiving. The entire FM band covers something like 40 MHz (40,000,000 Hz), with individual channels using only about 0.1 MHz. The region of the spectrum we think of as "radio frequency" spans the range from DC to 300 GHz (300,000,000,000 Hz) or so-- human transmissions show up as very narrow "spikes" on top of the broad radio background of the natural processes going on around us.

There are a handful of natural processes that produce narrow-band signals-- pulsars are a good example-- but they're easy to eliminate after detection. The key thing is the narrow bandwidth.

It's also got a good deal of stuff about the Allen Telescope Array, which will eventually include something like 350 telescopes designed to cover a broad range of frequencies, over a wide area of sky. It's an instrument optimized for the purpose of looking for alien radio signals, unlike most radio telescopes, which are generally more interested in resolution than broad coverage.

And, of course, there's a passing mention of Paul Allen, who put up $25 million for the telescope that bears his name. Have I mentioned that I want to be Paul Allen when I grow up? I don't want to be Bill Gates, who has to work very hard to stay atop the corporate world, and come up with new ways to break perfectly good software concepts. Being that guy would kind of suck-- being that guy's friend, who lucks into a couple of billion dollars that he can spend buying sports teams and space ships and radio telescopes, now, that's the way to go...

Anyway, check out the video. It's a good piece of work.